Control system and vehicle incorporating same

RELATED APPLICATION(S)

0001This application is a continuation-in-part of U.S. application Ser. No. 12/827,269, filed Jun. 30, 2010, the content of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

0002Embodiments of the present invention relate generally to motion control systems and, for example, to vehicles (e.g., lawn mowers) and motion control systems for accommodating relative movement between a working and a fixed portion of the vehicle.

BACKGROUND

0003Power vehicles for carrying out diverse tasks are known. For instance, power lawn mowers are well known for use in turf and lawn maintenance. Such mowers may range from small, walk-behind mowers such as those used by homeowners, to professional grade riding mowers adept at mowing larger areas. While embodiments of the present invention may be directed to control systems for use with a wide variety of power vehicles, it will, for the sake of brevity, be described with respect to power riding or walk-behind mowers.

0004Power mowers typically incorporate a prime mover (e.g., internal combustion engine) and a variable, e.g., hydraulic, drive system. The drive system may include left and right hydraulic motors coupled to left and right drive wheels, respectively. Power may be transmitted from the prime mover to the left and right hydraulic motors, e.g., via one or more pumps, to drive the left and right drive wheels independently. The rotational speed and direction of each drive wheel may then be controlled by associated drive control levers manipulated by an operator. By manipulating the control levers independently, each drive wheel can be separately driven forward or backwards at varying speeds. Thus, the mower may be propelled forwardly or in reverse. By powering one wheel in the forward direction and slowing, stopping, or powering the opposite wheel in the reverse direction, the mower can execute a turn.

0005With many conventional mowers, the engine and hydraulic pumps are attached to a frame of the mower, while the cutting deck is adjustably positionable at varying elevations relative to the frame to provide for different cutting heights. While effective, moving the cutting deck relative to the engine does have drawbacks. For example, with a belt-powered cutting deck, it is desirable to ensure that the fleeting angle (the belt angle formed between the engine driving sheave and the driven sheave(s) of the cutting deck) is maintained within an acceptable range as the deck moves up and down to minimize belt separation and/or wear. Depending on the distance between the engine and deck, the range of acceptable fleeting angles may be limited.

0006Another issue with some mowers concerns positioning of the drive control levers. For instance, each drive control lever may generally be positioned between a neutral and a full forward (and a full reverse) position. The levers are generally sized and configured so that the operator may manipulate the levers over their normal range of motion (e.g., from neutral to full forward) without relocating his or her hands. In the full forward position, the levers may be configured to rest against stationary stop bars. Such a configuration permits the operator to hold the levers against a fixed stop during normal operation, reducing potential fatigue in the hands, wrists, and arms. The fixed stop may also provide a degree of lever stability, minimizing inadvertent lever movement as a result of vehicle motion.

0007While effective, this full forward position may result in a vehicle speed in excess of what is desired for some mowing tasks. To reduce the speed, the operator may back the control levers off from the full forward position. Unfortunately, this technique may prevent the operator from resting the levers against the fixed stops. Alternatively, the engine throttle may be reduced. While throttle reduction is effective at reducing maximum vehicle speed, it also reduces the rotational speed of any attached implements, e.g., the blades of the cutting deck. As a result, cutting efficiency of the mower may be reduced.

SUMMARY

0008The present invention may overcome these and other issues with prior art mowers by providing, in one embodiment, a vehicle including: a chassis; a platform suspended from the chassis; and a platform displacement mechanism configured to move the platform, relative to the chassis, between a first position and a second position. A variable drive unit mounted to the platform may also be provided and include an input member movable, relative to a housing of the drive unit, between a first position and a second position. A control lever is attached to the chassis and operatively connected to the drive unit, the control lever configured to vary a position of the input member relative to the housing. The control lever is movable incrementally between a first position corresponding to the first position of the input member, and a second position corresponding to the second position of the input member. The vehicle also includes a control linkage system having a pivot link associated with the chassis and configured to pivot, relative to the chassis, about a main pivot axis. The linkage system further includes: a control link having a first end connected to the pivot link, and a second end connected to the control lever; and a drive link with a first end pivotally connected to the pivot link at a first drive link pivot, and a second end pivotally connected to the input member at a second drive link pivot. The linkage system is configured to maintain, as the platform is moved between its first and second positions, both a position of the input member relative to the drive unit, and a position of the control link relative to the chassis.

0009In another embodiment, a vehicle is provided including: a chassis supported by one or more drive wheels; a platform suspended from the chassis; and a platform lift mechanism configured to raise and lower the platform, relative to the chassis, between a first position and a second position. The vehicle also includes a variable drive unit attached to the platform and having an input arm that is pivotable, relative to a housing of the drive unit about an input pivot axis, between a first position and a second position. A prime mover is attached to either the platform or the chassis and operatively coupled to the drive unit to provide power to the same. A control lever is attached to the chassis and operatively connected to the drive unit, the control lever configured to vary a position of the input arm relative to the housing of the drive unit. The control lever is movable incrementally between a first position corresponding to the first position of the input arm, and a second position corresponding to the second position of the input arm. The vehicle also includes a drive motion control linkage system. The linkage system includes a bellcrank supported for pivoting relative to the chassis about a main pivot axis, wherein the bellcrank has a first arm and a second arm. The linkage system also includes a control link having a first end connected to the first arm at a control link pivot, and a second end connected to the control lever. An included drive link has a first end pivotally connected to the second arm of the bellcrank at a first drive link pivot for pivoting about a first drive link pivot axis, and a second end pivotally connected to the input arm at a second drive link pivot for pivoting about a second drive link pivot axis.

0010The above summary is not intended to describe each embodiment or every implementation of the present invention. Rather, a more complete understanding of the invention will become apparent and appreciated by reference to the following Detailed Description of Exemplary Embodiments and claims in view of the accompanying figures of the drawing.

BRIEF DESCRIPTION OF THE VIEWS OF THE DRAWING

0011The present invention will be further described with reference to the figures of the drawing, wherein:

0012<figref idref="DRAWINGS">FIG. 1</figref> is a rear perspective view of an exemplary vehicle, e.g., power walk-behind/stand-on mower, incorporating a control system, e.g., motion control linkage system, and a platform lift mechanism, in accordance with embodiments of the present invention, the mower illustrated with a standing platform in a deployed position;

0013<figref idref="DRAWINGS">FIG. 2</figref> is a front perspective view of the mower of <figref idref="DRAWINGS">FIG. 1</figref> illustrating an operator control area;

0014<figref idref="DRAWINGS">FIGS. 3A-3B</figref> (collectively referred to as <figref idref="DRAWINGS">FIG. 3</figref>) illustrate portions of an exemplary platform lift mechanism, wherein: <figref idref="DRAWINGS">FIG. 3A</figref> is a partial side elevation view of the platform lift mechanism; and <figref idref="DRAWINGS">FIG. 3B</figref> is a perspective view of a portion of the mechanism of <figref idref="DRAWINGS">FIG. 3A</figref>;

0015<figref idref="DRAWINGS">FIG. 4</figref> is a side elevation view of the mower of <figref idref="DRAWINGS">FIGS. 1 and 2</figref> with some structure removed to illustrate the platform lift mechanism, the motion control linkage system, and the control area;

0016<figref idref="DRAWINGS">FIG. 5</figref> is an enlarged view of the control area of <figref idref="DRAWINGS">FIG. 4</figref>;

0017<figref idref="DRAWINGS">FIG. 6</figref> is a partial perspective view of the mower of <figref idref="DRAWINGS">FIGS. 1 and 2</figref> illustrating the motion control linkage system;

0018<figref idref="DRAWINGS">FIG. 7</figref> is a partial enlarged side elevation view of the mower of <figref idref="DRAWINGS">FIGS. 1 and 2</figref> illustrating the platform in a first or fully raised position, and the motion control linkage system in both a first or neutral position (solid lines) and a second or maximum forward position (broken lines);

0019<figref idref="DRAWINGS">FIG. 8</figref> is a partial enlarged side elevation view similar to <figref idref="DRAWINGS">FIG. 7</figref> but with the platform shown in a second or fully lowered position, and the motion control linkage system shown in the first or neutral position;

0020<figref idref="DRAWINGS">FIG. 9</figref> is a partial side elevation view of the control area with a control lever shown in the first or neutral position and a control lever stop bar shown in a first position “A”;

0021<figref idref="DRAWINGS">FIG. 10</figref> is a partial side elevation view of the control area similar to <figref idref="DRAWINGS">FIG. 9</figref> but with the control lever shown in the first or neutral position and the control lever stop bar shown in a second position “B;”

0022<figref idref="DRAWINGS">FIGS. 11A-11B</figref> are rear perspective views of a vehicle (e.g., power mower) incorporating a control system, e.g., motion control linkage system, in accordance with another embodiment of the invention (with various vehicle structure removed for clarity), wherein: <figref idref="DRAWINGS">FIG. 11A</figref> illustrates the control area as well as the linkage system; and <figref idref="DRAWINGS">FIG. 11B</figref> is an enlarged view of the linkage system of <figref idref="DRAWINGS">FIG. 11A</figref>;

0023<figref idref="DRAWINGS">FIG. 12</figref> is a front perspective view of the vehicle and linkage system of <figref idref="DRAWINGS">FIGS. 11A-11B</figref>;

0024<figref idref="DRAWINGS">FIG. 13</figref> is side elevation view of the vehicle and linkage system of <figref idref="DRAWINGS">FIGS. 11A-11B</figref> illustrating the platform in a first or fully raised position, and the linkage system in a first or neutral position;

0025<figref idref="DRAWINGS">FIG. 14</figref> is a partial side elevation view similar to that of <figref idref="DRAWINGS">FIG. 13</figref>, but illustrating the linkage system in a second or maximum forward position;

0026<figref idref="DRAWINGS">FIG. 15</figref> is side elevation view of the vehicle and linkage system of <figref idref="DRAWINGS">FIGS. 11A-11B</figref> illustrating the platform in a second or fully lowered position, and the linkage system in a first or neutral position; and

0027<figref idref="DRAWINGS">FIG. 16</figref> is a partial side elevation view similar to that of <figref idref="DRAWINGS">FIG. 15</figref>, but illustrating the linkage system in the second or maximum forward position.

0028The figures are rendered primarily for clarity and, as a result, are not necessarily drawn to scale. Moreover, certain structure (e.g., various chassis portions/components, fasteners, bearings, cables, and hydraulic components (including but not limited to: conduits; hoses; and fittings, etc.)) may be removed from some or all of the views to better illustrate aspects of the depicted embodiments, or where inclusion of such structure/components is not necessary to an understanding of the various embodiments of the invention. The removal of such structure/components, however, is not to be interpreted as limiting the scope of the invention in any way.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

0029In the following detailed description of illustrative embodiments of the invention, reference is made to the accompanying figures of the drawing which form a part hereof, and in which are shown, by way of illustration, specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the instant invention.

0030Embodiments of the present invention are generally directed to vehicles such as lawn mowers and the like, and to motion control systems for use with the same. Embodiments of the present invention may include a linkage-based motion control system for accurately adjusting a parameter (e.g., velocity) of the vehicle even as a geometric relationship between an input (e.g., velocity control lever) and an output (e.g., drive train) of the vehicle is modified. As a result, the vehicle may respond to a given operator input in a repeatable manner regardless of the vehicle's geometric configuration.

0031While the exemplary motion control linkage systems are described and illustrated herein as velocity control systems, alternative embodiments may address systems for controlling most any parameter wherein a location of a control input may be varied relative to the associated controlled device.

0032Other embodiments may further include an adjustable stop bar for use with adjusting a terminal position of a control lever (e.g., a velocity control lever). Accordingly, the maximum potential speed of the vehicle may be adjusted without altering a throttle setting of the vehicle.

0033<figref idref="DRAWINGS">FIG. 1</figref> illustrates an exemplary self-propelled vehicle, e.g., a walk-behind or ride-on lawn mowing vehicle <b>100</b> that may incorporate a motion control linkage system <b>300</b> (see <figref idref="DRAWINGS">FIG. 4</figref>) in accordance with one embodiment of the present invention. While, for the sake of brevity, embodiments of the invention are herein described with respect to a walk-behind/stand-on lawn mower (hereinafter generically referred to merely as a “mower”), those of skill in the art will realize that the invention is equally applicable to other types of walk-behind, ride-behind (e.g., such as those utilizing sulkies), and conventional ride-on mowers, as well as to most any other walk-behind, ride-behind, or ride-on self-propelled utility vehicle (e.g., aerator, snow blower, blower/vacuum, spreader, etc.).

0034While the general construction of the mower <b>100</b> is not necessarily central to an understanding of the invention (e.g., other mower configurations may be utilized without departing from the scope of the invention), one configuration is now briefly described. The mower <b>100</b> may also be, in some respects, similar to the mowers described in U.S. patent application Ser No. 12/275,381, the content of which is incorporated herein by reference in its entirety.

0035<figref idref="DRAWINGS">FIGS. 1 and 2</figref> illustrate the exemplary mower <b>100</b> having a chassis <b>102</b> and a power source or prime mover, e.g., internal combustion engine <b>104</b>. A pair of transversely opposing, ground engaging drive members, e.g., first and second drive wheels <b>106</b>, may be coupled for rotation to opposing sides of the chassis to support and propel the mower <b>100</b> relative to a ground surface <b>103</b>. Each drive wheel <b>106</b> may be powered by its own hydraulic wheel motor <b>107</b> (only right side motor <b>107</b><i>b </i>shown in <figref idref="DRAWINGS">FIG. 1</figref>) attached to the chassis <b>102</b> that receives power from, at least in one embodiment, its own variable drive unit, e.g., hydraulic drive unit such as a hydraulic pump <b>110</b> (see <figref idref="DRAWINGS">FIGS. 4 and 6</figref>), that is itself powered by the engine <b>104</b>. While described herein as a hydraulic drive unit, other embodiments may utilize other variable drive units, e.g., electrical or mechanical systems, without departing from the scope of the invention.

0036The pumps <b>110</b> and the engine <b>104</b> may be mounted or attached to a platform <b>112</b> (see <figref idref="DRAWINGS">FIG. 4</figref>) that, as described in more detail below, is suspended from, and movable relative to, the chassis <b>102</b> via a platform displacement, e.g., lift, mechanism. Alternatively, one or both of the pumps and engine could be attached to the chassis. The engine <b>104</b> may include an output shaft having a sheave (not shown) that provides power to an input sheave <b>118</b> on each pump <b>110</b> via an endless belt <b>117</b> as represented in broken lines in <figref idref="DRAWINGS">FIG. 7</figref>. In the illustrated embodiment, the platform <b>112</b> may be raised and lowered between a first and a second position by the platform lift mechanism.

0037As used herein, relative terms such as “left,” “right,” “fore,” “forward,” “aft,” “rearward,” “top,” “bottom,” “upper,” “lower,” “horizontal,” “vertical,” and the like are from the perspective of one operating the mower <b>100</b> while the mower is in an operating configuration, e.g., while the mower <b>100</b> is positioned such that the wheels <b>106</b> and <b>108</b> rest upon the generally horizontal ground surface <b>103</b> as shown in <figref idref="DRAWINGS">FIGS. 1 and 2</figref>. These terms are used herein to simplify the description, however, and not to limit the scope of the invention in any way.

0038Moreover, the suffixes “a” and “b” may be used throughout this description to denote various left- and right-side parts/features, respectively. However, in most pertinent respects, the parts/features denoted with “a” and “b” suffixes are substantially identical to, or mirror images of, one another. It is understood that, unless otherwise noted, the description of an individual part/feature (e.g., part/feature identified with an “a” suffix) also applies to the opposing part/feature (e.g., part/feature identified with a “b” suffix). Similarly, the description of a part/feature identified with no suffix may apply, unless noted otherwise, to both the corresponding left and right part/feature.

0039Operator controls, some of which are described below, may permit independent control of the speed and direction of each drive wheel <b>106</b> (e.g., each pump <b>110</b>), allowing control of mower <b>100</b> speed and direction from either a walking or riding (e.g., standing) position generally behind the mower <b>100</b>. A pair of front swiveling caster wheels <b>108</b> (only right wheel visible in <figref idref="DRAWINGS">FIG. 1</figref>), which may be connected to forwardly extending chassis rails, may support the front of the mower <b>100</b> in rolling engagement with the ground surface <b>103</b>.

0040Although the illustrated mower has the drive wheels <b>106</b> in the rear and caster wheels <b>108</b> in front, this configuration is not limiting. For example, other embodiments may reverse the location of the wheels, e.g., drive wheels in front and driven or passive wheels in back. Moreover, other configurations may use different wheel configurations altogether, e.g., a tri-wheel configuration. Moreover, while the mower <b>100</b> is illustrated as incorporating a hydraulic drive system, other drive systems, e.g., gear or pulley driven systems, may also be utilized without departing from the scope of the invention.

0041A lawn mower cutting deck <b>114</b> may be mounted to a lower side of the platform <b>112</b> generally longitudinally between the drive wheels <b>106</b> and the caster wheels <b>108</b>. The cutting deck <b>114</b> may include one or more cutting blades <b>115</b> (see, e.g., <figref idref="DRAWINGS">FIG. 4</figref>) as is known in the art. The cutting blades may be operatively powered, via spindles passing through the deck, by a belt <b>116</b> (see also <figref idref="DRAWINGS">FIG. 4</figref>) driven by the engine <b>104</b>. During operation, power is selectively delivered to the cutting deck <b>114</b>, whereby the blades <b>115</b> rotate at a speed sufficient to sever grass and other vegetation passing beneath the cutting deck.

0042The exemplary mower <b>100</b> may also include a standing platform <b>120</b> that may be moved between a deployed position as shown in <figref idref="DRAWINGS">FIGS. 1 and 2</figref>, and a stowed position (not shown). In the deployed position, an operator may stand upon the standing platform <b>120</b> during vehicle operation. Alternatively, the standing platform <b>120</b> may be moved to the stowed position to accommodate the operator in a walk-behind configuration.

0043As shown in <figref idref="DRAWINGS">FIG. 2</figref>, the mower <b>100</b> may further include an operator control area <b>200</b>. In the illustrated embodiment, the control area <b>200</b> may include various operator controls that are mounted to upwardly extending portions of the chassis <b>102</b> near the rearward end of the mower such that the controls are located within comfortable reach of the operator standing either behind the mower or upon the platform <b>120</b>.

0044The control area <b>200</b> may include any number of controls necessary or beneficial to the operation of the mower <b>100</b>. For instance, a parking brake handle <b>202</b> (see <figref idref="DRAWINGS">FIG. 2</figref>) may selectively activate a brake (e.g., brake members <b>122</b> shown in <figref idref="DRAWINGS">FIGS. 1 and 2</figref>) when the mower is parked. Other controls, including for example, a throttle lever to control the speed of the engine <b>104</b>, engine choke, hour meter, and PTO deck engagement control (to initiate and terminate power delivery to the cutting blades of the mower deck <b>114</b>) may also be provided. Still further, one or more control levers, e.g., drive control levers <b>302</b><i>a </i>and <b>302</b><i>b</i>, may be provided. The drive control levers <b>302</b> may be attached, e.g., pivotally attached, to the chassis <b>102</b> and be configured to control the speed and direction of the drive wheels <b>106</b><i>a </i>and <b>106</b><i>b</i>, respectively, (e.g., via their associated pumps <b>110</b><i>a </i>and <b>110</b><i>b</i>) as described in more detail below.

0045As shown in <figref idref="DRAWINGS">FIG. 3A</figref>, a platform displacement or lift mechanism <b>220</b> may also be provided to permit the operator to move (e.g., raise and lower) the platform <b>112</b>, and thus the cutting deck <b>114</b>, relative to the chassis <b>102</b> between at least a first and second position. In the illustrated embodiment, the mechanism may be manipulated by an adjustment lever <b>204</b> that is itself pivotally attached to the chassis <b>102</b> at a pivot <b>222</b> near the control area <b>200</b>. In the illustrated embodiment, the mower may further include a pin, e.g., tethered pin <b>227</b> (see <figref idref="DRAWINGS">FIG. 2</figref>) operable to engage one of many openings <b>226</b> formed in a plate <b>224</b> of the frame. To reposition the lever <b>204</b> (and thus the platform <b>112</b>), the lever may be manually lifted upwardly to expose the opening <b>226</b> corresponding to the desired platform height. Once the platform is located at or slightly above the desired height, the pin <b>227</b> may be inserted into the appropriate opening <b>226</b>. By then releasing the lever <b>204</b>, the weight of the platform <b>112</b> may then rest against the pin to maintain the platform at the desired height. While illustrated herein as incorporating a manual platform lift mechanism, other embodiments may substitute a powered, e.g., hydraulic or electric lift mechanism, without departing from the scope of the invention.

0046As used herein, the term “pivot” refers to most any structure or feature that permits one component to pivot or rotate relative to another. The pivots described and illustrated herein may be configured in most any manner that permits such relative motion. For instance, an axle, bolt, or shaft, optionally surrounded by a bushing or bearing, may be used to form the pivot. As various pivot configurations are well known in the art, further detail regarding these components as they relate to embodiments of the present invention are not provided herein. Moreover, for illustration purposes, a pivot may be identified in the figures by pointing either to the general structure defining the pivot, or to a pivot axis defined by the pivot. Further, any measurements identified herein that are indexed relative to a pivot are understood to be measured from/to the pivot axis of the respective pivot and in a direction orthogonal to the pivot axis.

0047As shown in the embodiment of <figref idref="DRAWINGS">FIGS. 3A and 3B</figref>, the lever <b>204</b> may be pivotally attached, at a distance offset from the pivot <b>222</b>, to a connecting rod <b>228</b>. At a lower end, the connecting rod <b>228</b> may be pivotally connected, via a pivot <b>229</b> (see also <figref idref="DRAWINGS">FIG. 3B</figref>), to a rear platform link or bellcrank <b>230</b>. The rear bellcrank is, in turn, itself pivotally attached to the chassis <b>102</b> at a platform chassis pivot <b>232</b> defining a platform chassis pivot axis <b>243</b>. A first end <b>234</b> of the rear platform bellcrank <b>230</b> may be pivotally attached to a tie rod <b>236</b> extending forwardly where it attaches to a first end <b>238</b> of a similar front platform link or bellcrank <b>240</b>. The front platform bellcrank <b>240</b> may also, like the bellcrank <b>230</b>, be pivotally attached to the chassis <b>102</b> at a platform chassis pivot <b>242</b> also defining a platform chassis pivot axis. A second end <b>244</b> of the front platform bellcrank <b>240</b> and a second end <b>248</b> of the rear platform bellcrank <b>230</b> may be pivotally attached to the platform <b>112</b> at a platform attachment point, e.g., platform pivot <b>247</b> defining a platform pivot axis <b>245</b>. In the illustrated embodiment, the front platform/deck bellcrank <b>240</b> may utilize an intermediate bracket <b>246</b> as shown in <figref idref="DRAWINGS">FIG. 3A</figref>.

0048The front platform bellcrank <b>240</b> may be of the same size and geometry as the rear platform bellcrank <b>230</b> and, as a result of the tie rod <b>236</b>, may be oriented similarly. Accordingly, movement of the lever <b>204</b> downwardly (e.g., in the clockwise direction in <figref idref="DRAWINGS">FIG. 3A</figref>) may result in pivotal movement of the front and rear platform bellcranks <b>230</b>, <b>240</b> about the pivots <b>232</b> and <b>242</b>, respectively, in the clockwise direction, effectively lowering the platform <b>112</b> and the deck <b>114</b>. Conversely, raising the lever <b>204</b>, e.g., pivoting it in a counterclockwise direction about the pivot <b>222</b>, results in raising the platform <b>112</b> and deck <b>114</b>.

0049As illustrated in <figref idref="DRAWINGS">FIG. 3B</figref>, the second end <b>248</b> of the rear platform bellcrank <b>230</b> may support (e.g., be welded or otherwise integral with or fixed to) a shaft <b>251</b> that extends transversely across the mower <b>100</b>. The shaft <b>251</b> may extend from the rear platform bellcrank <b>230</b> through a transversely spaced link <b>249</b> and through one or more brackets <b>254</b> (e.g., one on each side of the platform) that support the platform <b>112</b>. The brackets <b>254</b> may hang on the shaft <b>251</b>, thereby providing an effective pivoting relationship (between the platform <b>112</b> and the bellcrank <b>230</b>) about the centerline of the shaft. The link <b>249</b> may, at a first end, be welded to the shaft <b>251</b>, and at its opposite end, connect to a shaft that defines the pivot <b>229</b>. On the opposite side of the mower <b>100</b>, the shaft <b>251</b> may connect to a similar or identical mechanism (e.g., to another front and rear platform bellcrank <b>230</b>, <b>240</b>, link <b>249</b>, and another tie rod <b>236</b> (see <figref idref="DRAWINGS">FIGS. 3A and 3B</figref>)) on the opposite side of the mower).

0050As a result of the described geometry, the platform <b>112</b> and deck <b>114</b> may be attached and lifted relative to the chassis <b>102</b> at four separate lift points. Moreover, the respective front and rear platform bellcranks <b>230</b>, <b>240</b> and tie rods <b>236</b> may form a 4-bar linkage on each side of the mower <b>100</b> that keeps the platform <b>112</b> generally level at any selected elevation (even though described as “level,” the platform may be configured such that it is slightly but equally inclined (e.g., inclined forwardly) at all elevation settings).

0051To assist the operator with raising and lowering the platform <b>112</b>/deck <b>114</b>, springs <b>250</b> may optionally be provided on one or both sides of the mower <b>100</b>. An upper end of each spring may attach to the chassis <b>102</b> (see <figref idref="DRAWINGS">FIG. 1</figref>), while a lower end of each spring may operatively connect to the lever arms(s) <b>230</b>, e.g., it may connect to a chain that is attached to an auxiliary lever arm <b>252</b>. The lever arm <b>252</b> may be rigidly attached to (e.g., via a connecting tube), but transversely offset from, the lever arm <b>230</b> as shown in <figref idref="DRAWINGS">FIG. 3B</figref> so that it pivots in unison with the rear bellcrank.

0052Using the exemplary platform lift mechanism <b>220</b> described and illustrated herein, the platform <b>112</b> may move along a path defined by an arc <b>255</b> (see <figref idref="DRAWINGS">FIG. 3A</figref>) as the platform is raised and lowered. This arc may be defined by a linear distance <b>256</b> between the axis of the platform chassis pivot <b>232</b> (or <b>242</b>) and the axis of the platform attachment point/pivot <b>247</b> of the respective platform bellcrank <b>230</b> (or <b>240</b>). In the illustrated embodiment, the distance <b>256</b> is identical for all (e.g., both front and rear) platform bellcranks.

0053As described elsewhere herein, the engine <b>104</b>, cutting deck <b>114</b>, and hydraulic pumps <b>110</b> (see <figref idref="DRAWINGS">FIGS. 4 and 6</figref>) may all be attached to the platform <b>112</b> and thus move up and down as the platform lift system <b>220</b> is manipulated (see also <figref idref="DRAWINGS">FIGS. 7 and 8</figref>). This may, as stated elsewhere herein, provide for relatively planar belt <b>116</b> routing between these components, reducing belt wear and potential belt roll-off that may occur in systems having greater fleeting angles. However, as the hydraulic pumps <b>110</b> move relative to the chassis <b>102</b> and thus to the control levers, a conventional linkage may cause unintended movement of input arms <b>332</b> of the pumps <b>110</b> (see, e.g., <figref idref="DRAWINGS">FIG. 7</figref>) merely as a result of platform repositioning.

0054Motion control linkage systems in accordance with embodiments of the present invention may, however, avoid these problems, i.e., they may provide consistent and repeatable input to the hydraulic pumps <b>110</b>, for a given position of the respective drive control levers <b>302</b>, regardless of platform location. As a result, consistent mower response may be provided.

0055As shown in <figref idref="DRAWINGS">FIGS. 1</figref>, <b>2</b>, and <b>4</b>, the exemplary motion control linkage system <b>300</b> may include a first or left drive control lever <b>302</b><i>a </i>and a second or right drive control lever <b>302</b><i>b </i>pivotally attached to the chassis <b>102</b>. The control levers <b>302</b> may be configured to pivot about a transverse horizontal axis <b>307</b> (see <figref idref="DRAWINGS">FIG. 6</figref>) from a first or neutral position towards both a first or forward stop bar <b>304</b>, and a second or rearward stop bar <b>306</b>. One or both of the control levers <b>302</b> (e.g., <b>302</b><i>b </i>as shown in <figref idref="DRAWINGS">FIG. 2</figref>) could be biased for pivotal outward movement (e.g., in a direction <b>309</b> about an axis generally parallel to a longitudinal axis of the mower <b>100</b>). Such a configuration may permit, upon pivotal inward movement of the control lever <b>302</b><i>b </i>by the operator to the position shown in <figref idref="DRAWINGS">FIGS. 1 and 2</figref>, activation of an operator presence switch (not shown). As is recognized in the art, activation of the switch may be requisite to activation of some of the mower subsystems.

0056The control levers <b>302</b> may also be biased to the intermediate, neutral position between the two stop bars <b>304</b> and <b>306</b> for mower operation as shown in <figref idref="DRAWINGS">FIGS. 1</figref>, <b>2</b> and <b>4</b>. Each control lever <b>302</b> may be movable between at least the first or neutral position (shown in <figref idref="DRAWINGS">FIG. 4</figref>), which corresponds to a first or zero forward velocity of its respective drive wheel <b>106</b>/pump <b>110</b> (e.g., input arm <b>332</b>), and a second or engaged position (abutting the forward stop bar <b>304</b>), which corresponds to a second or maximum forward velocity of its respective drive wheel/pump (e.g., input arm <b>332</b>). Stated another way, each control lever <b>302</b> may independently vary a velocity of its respective drive wheel <b>106</b> incrementally between a first or zero forward velocity and a second or predetermined maximum forward velocity without varying the engine throttle. Each lever <b>302</b> may additionally be movable to a third position (abutting the rear stop bar <b>306</b>) corresponding to a third or predetermined maximum reverse velocity of its respective drive wheel. In the illustrated embodiment, the neutral position of the control levers <b>302</b> may be located more closely to the rearward stop bar <b>306</b> to provide a greater range of movement for forward travel.

0057<figref idref="DRAWINGS">FIG. 5</figref> illustrates an enlarged partial view of the control area of <figref idref="DRAWINGS">FIG. 4</figref>. As illustrated in this view, each control lever <b>302</b> may pivot relative to the chassis <b>102</b> at the transverse horizontal axis <b>307</b> (see also <figref idref="DRAWINGS">FIG. 6</figref>) defined by a pivot <b>308</b>. Each control lever <b>302</b> may also include a secondary lever arm <b>310</b> (which is offset from the pivot <b>308</b>) that pivotally receives an upper end of a control link <b>312</b> at a pivot <b>313</b>. The control link <b>312</b> may be segmented and include an adjustment mechanism <b>314</b> to lengthen or shorten the control link after installation. As one can appreciate from <figref idref="DRAWINGS">FIG. 5</figref>, movement of the control lever <b>302</b> towards the forward stop bar <b>304</b> (or towards the rear stop <b>306</b>) results in movement of the control link upwardly (or downwardly) as indicated by the arrows in this view.

0058<figref idref="DRAWINGS">FIG. 6</figref> illustrates a perspective view of the motion control linkage system <b>300</b>. The platform <b>112</b> and the pumps <b>110</b> are also illustrated in this view. However, various other structures, e.g., engine <b>104</b> and most of the chassis <b>102</b>, are removed for visibility. As this view illustrates, the control system <b>300</b> may include independent linkage systems for each side of the mower <b>100</b>, e.g., for each control lever <b>302</b> and its associated pump <b>110</b>. While the system <b>300</b> is illustrated in the figures as including dual mechanisms to independently control the drive wheel <b>106</b> on each side of the mower <b>100</b>, control systems for alternate applications may utilize a single linkage without departing from the scope of the invention.

0059<figref idref="DRAWINGS">FIG. 7</figref> is an enlarged view of a portion of the mower of <figref idref="DRAWINGS">FIG. 4</figref>. This view illustrates a lower portion of one side of the control linkage system <b>300</b> that operatively connects one control link <b>312</b> (e.g., link <b>312</b><i>b</i>) to its respective pump <b>110</b> (e.g., pump <b>110</b><i>b</i>). As shown in this view, a pivot link, e.g., bellcrank <b>316</b>, may be pivotally attached to the chassis <b>102</b>, or otherwise operatively attached such that it pivots relative to the chassis, at a main or chassis pivot <b>318</b> for pivoting about a horizontal transverse, main pivot axis <b>320</b> (see <figref idref="DRAWINGS">FIG. 6</figref>). Each bellcrank <b>316</b> may include a first arm defining a first end <b>322</b> that is offset from the main pivot <b>318</b>. The first arm of the bellcrank may be pivotally connected to a proximal end of the control link <b>312</b> at a control link pivot <b>324</b> defining a control link pivot axis. The bellcrank <b>316</b> may also include a second arm defining a second end <b>326</b> pivotally connected to a first end <b>327</b> of a drive link <b>328</b> at a first drive link pivot <b>330</b> defining a first drive link pivot axis. A second end <b>329</b> of the drive link <b>328</b> may pivotally connect to a distal end of the pump input member or arm <b>332</b> at a second drive link pivot <b>334</b> defining a second drive link pivot axis. The input arm <b>332</b> may move, e.g., pivot, about an input pivot <b>333</b> defining an input pivot axis, relative to a housing of the pump, thereby repositioning an internal swashplate within the pump to alter the flow of hydraulic fluid delivered to the respective wheel motor <b>107</b> (see also <figref idref="DRAWINGS">FIG. 1</figref>). In the illustrated embodiment, the drive link may be curvilinear in shape to better accommodate the mower configuration. However, other shapes, e.g., straight, are certainly possible without departing from the scope of the invention.

0060The solid line representation of the drive link <b>328</b> and bellcrank <b>316</b> in <figref idref="DRAWINGS">FIG. 7</figref> represents the geometry of the system <b>300</b> when the drive control lever <b>302</b> is in the first or neutral position (see solid line representation of the control lever <b>302</b> in <figref idref="DRAWINGS">FIG. 5</figref>). Conversely, the broken line representation of the drive link <b>328</b> and bellcrank <b>316</b> in <figref idref="DRAWINGS">FIG. 7</figref> represents the geometry of the system <b>300</b> when the drive control lever <b>302</b> is in the second or engaged position (see broken line representation of the control lever <b>302</b> in <figref idref="DRAWINGS">FIG. 5</figref>). Thus, movement of the control levers <b>302</b> may vary a position of the respective pump input arm <b>332</b> relative to the pump housing. For instance, as is evident in <figref idref="DRAWINGS">FIG. 7</figref>, incremental movement of the drive control lever <b>302</b> from the first or neutral position to the second or engaged position causes the pump input arm <b>332</b> (to which the drive link <b>328</b> is attached) to pivot, relative to the pump housing, from a first or pump neutral position (wherein the pump input arm is approximately vertical, e.g., about 12 o'clock in <figref idref="DRAWINGS">FIG. 7</figref>), to an adjustable second or maximum position (wherein the pump input arm is rotated slightly clockwise in <figref idref="DRAWINGS">FIG. 7</figref>, e.g., to about one o'clock as shown in broken lines). This relationship between control levers <b>302</b> and their respective input arms <b>332</b> exists regardless of whether the platform is in (or is moving between) the first position, the second position or any intermediate position.

0061<figref idref="DRAWINGS">FIG. 8</figref> is a view similar to <figref idref="DRAWINGS">FIG. 7</figref>, but with the platform <b>112</b> shown at its second or lowest position (as opposed to the first or highest position shown in <figref idref="DRAWINGS">FIG. 7</figref>) and the drive control lever <b>302</b>/system <b>300</b> shown in the neutral position. The platform height adjustment may be accommodated as described elsewhere herein, e.g., with the lift mechanism <b>220</b> illustrated in <figref idref="DRAWINGS">FIGS. 3A-3B</figref>. Once again, as the platform <b>112</b> and deck <b>114</b> move from the elevation of <figref idref="DRAWINGS">FIG. 7</figref> to the elevation of <figref idref="DRAWINGS">FIG. 8</figref>, movement occurs along the arc <b>255</b> defined by the distance <b>256</b> of each of the bellcranks <b>230</b> and <b>240</b> (see also <figref idref="DRAWINGS">FIG. 3A</figref>). Moreover, as the platform/cutting deck move, each drive link <b>328</b> may pivot about the first drive link pivot <b>330</b> from the position shown in solid lines in <figref idref="DRAWINGS">FIG. 7</figref> to the position shown in <figref idref="DRAWINGS">FIG. 8</figref>.

0062In the embodiment illustrated in <figref idref="DRAWINGS">FIGS. 7 and 8</figref>, the drive link <b>328</b> has an effective length <b>336</b> (e.g., linear distance measured between the axes of the first and second drive link pivots <b>330</b> and <b>334</b>) that is equal to the effective length <b>256</b> of the platform bellcranks. Moreover, a line <b>257</b> (see <figref idref="DRAWINGS">FIG. 8</figref>) extending orthogonally between axes of each platform chassis pivot <b>232</b>/<b>242</b> and its associated platform pivot <b>247</b> may be parallel to a line <b>258</b> extending orthogonally between the respective axes of the first and second drive link pivots <b>330</b> and <b>334</b>.

0063Furthermore, as illustrated in <figref idref="DRAWINGS">FIG. 8</figref>, a linear distance <b>337</b> between the axis of the input pivot <b>333</b> and the axis of the second drive link pivot <b>334</b> may be equal to a linear distance <b>338</b> between the axis <b>320</b> of the main pivot <b>318</b> and the axis of the first drive link pivot <b>330</b>, while a line <b>260</b> extending between the axis of the input pivot <b>333</b> and the axis of the second drive link pivot <b>334</b> may be parallel to a line <b>262</b> extending between the axis of the main pivot <b>318</b> and the axis of the first drive link pivot <b>330</b>.

0064As a result of this geometry, the drive link <b>328</b> may accommodate pivoting of the platform <b>112</b> without imparting any unintended displacement to the input arm <b>332</b> of the pump. Thus, the platform <b>112</b>/cutting deck <b>114</b> may be moved to any available height without altering the position of the pump input arm <b>332</b>. The linkage system may therefore maintain, as the platform <b>112</b> is moved between its first and second positions, both the position of the input member <b>332</b> relative to the drive unit <b>110</b>, and a position of the control link <b>312</b> (as well as the control lever <b>302</b>) relative to the chassis <b>102</b>.

0065While the control system is shown only in the neutral position in <figref idref="DRAWINGS">FIG. 8</figref>, the same result may occur regardless of the position of the drive control lever <b>302</b>. For instance, placement of the drive control lever <b>302</b> in the second (e.g., forward) or engaged position (broken lines in <figref idref="DRAWINGS">FIG. 5</figref>) with the platform <b>112</b> at its lowest setting as shown in <figref idref="DRAWINGS">FIG. 8</figref> would result in positioning the pump input arm <b>332</b> in the same location as it is positioned when the platform is at its highest setting (see broken line rendering in <figref idref="DRAWINGS">FIG. 7</figref>). In fact, the platform <b>112</b> could even be repositioned during operation (while the control handles remain in a given position) without any effect on pump configuration/mower speed.

0066In some embodiments, the motion control linkage system <b>300</b> may further include a velocity limiting mechanism, an exemplary embodiment of which will now be described with reference to <figref idref="DRAWINGS">FIGS. 9 and 10</figref>. Generally speaking, the velocity limiting mechanism permits the operator to limit or adjust a maximum potential forward velocity of the mower (the speed resulting when the levers <b>302</b> are resting against the forward stop bar <b>304</b>) without varying the engine throttle.

0067In the illustrated embodiment, the velocity limiting mechanism is configured as a selectively pivotable forward stop bar <b>304</b> defining a stop surface against which the drive control levers may rest when in the second or engaged position. When in a first or maximum potential velocity position “A”, the forward stop bar <b>304</b> is positioned at a first distance from the drive control lever <b>302</b> (when the latter is in the neutral position) as shown in <figref idref="DRAWINGS">FIG. 9</figref>. In a second or reduced maximum potential velocity position “B”, the forward stop bar <b>304</b> is positioned at a second distance from the drive control lever <b>302</b> that is less than the first distance as shown in <figref idref="DRAWINGS">FIG. 10</figref>.

0068As a result, when the operator wants to reduce the potential maximum speed of the mower (e.g., to conduct operator training or to address cut quality under various mowing conditions) but still wishes to maintain optimal engine speed and/or the comfort associated with holding the drive control levers against the fixed stop bar <b>304</b>, the forward stop bar can be repositioned as shown in <figref idref="DRAWINGS">FIG. 10</figref> (or repositioned to any intermediate position). Repositioning the forward stop bar from position A of <figref idref="DRAWINGS">FIG. 9</figref> to position B of <figref idref="DRAWINGS">FIG. 10</figref> may, in one embodiment, reduce the maximum potential speed of the mower (for a given throttle setting) from a first maximum vehicle speed setting, e.g., about eight miles/hour, to a second or reduced maximum vehicle speed setting, e.g., about four miles/hour.

0069In one embodiment, the forward stop bar <b>304</b> is pivotally attached to the mower chassis <b>102</b> for pivoting about a transverse pivot axis that is coincident with the pivot axis <b>307</b> (see <figref idref="DRAWINGS">FIG. 6</figref>) of the drive control levers <b>302</b>. As a result, the stop bar <b>304</b>, independent of its position, stays within the same arc of rotation as that in which the levers <b>302</b> move. Accordingly, each drive control lever <b>302</b> contacts the stop bar <b>304</b> at the same location regardless of the stop bar position. By avoiding all but movement about a common axis for both the drive control levers <b>302</b> and the stop bar <b>304</b>, comfortable and repeatable positioning of the drive control levers relative to the stop bar is maintained.

0070While not illustrated herein, the stop bar <b>304</b> could be split such that a separate stop bar is provided for each of the drive control levers <b>302</b>. Moreover, the mower <b>100</b> could also include an adjustable rear stop bar (not shown) to adjust the maximum rearward velocity of the mower (e.g., the maximum rearward velocity resulting from pulling the drive control levers to a fully aft position).

0071The velocity limiting mechanism may also include a lock mechanism to secure the forward stop bar <b>304</b> in place. In one embodiment, the forward stop bar <b>304</b> includes a bracket <b>340</b> that sits along one or both sides of the chassis <b>102</b>. The bracket may define a slot <b>342</b> through which a clamp <b>344</b> passes and threads to the chassis <b>102</b>. By loosening the clamp <b>344</b>, the forward stop bar <b>304</b> may pivot within the confines defined by the clamp sitting within the slot <b>342</b>. By tightening the clamp <b>344</b>, the stop bar may be locked in position A of <figref idref="DRAWINGS">FIG. 9</figref>, position B of <figref idref="DRAWINGS">FIG. 10</figref>, or any intermediate position. The slot <b>342</b> may include detents or the like to indicate discrete locations, or may permit generally infinite positioning.

0072<figref idref="DRAWINGS">FIGS. 11A-16</figref> illustrate partial views of a vehicle, e.g., a power lawn mower <b>1000</b>, in accordance with another embodiment of the invention. Except as identified below, the mower <b>1000</b> may be substantially identical to the mower <b>100</b> already described herein. For instance, it may utilize a hydraulic drive system having two hydraulic pumps <b>110</b> and two wheel motors <b>107</b> that are substantially identical to the like components already described herein. Moreover, the mower <b>1000</b> may include the chassis <b>102</b>, the platform <b>112</b>, and the control area <b>200</b> as already described herein, as well as a platform displacement mechanism <b>1220</b> (see <figref idref="DRAWINGS">FIGS. 13 and 15</figref>) configured to move the platform between first and second positions in a manner similar in most respects to the mechanism <b>220</b> described herein and illustrated in <figref idref="DRAWINGS">FIGS. 3A-3B</figref>.

0073As these common features/subsystems have already been described and illustrated with respect to the vehicle <b>100</b>, further description/illustration of such aspects as they apply to the vehicle <b>1000</b> may not be addressed in detail herein. However, it is understood that these and other portions of the vehicle <b>100</b> (e.g., the cutting deck <b>114</b>, motor <b>104</b>, control area <b>200</b>, hydraulic subsystems, etc.) may also form part of the vehicle <b>1000</b> even though not explicitly illustrated in <figref idref="DRAWINGS">FIGS. 11A-16</figref>.

0074As further described below, the vehicle <b>1000</b> may differ from the vehicle <b>100</b> in that it may substitute, in place of the motion control linkage system <b>300</b>, a motion control linkage system <b>400</b> as described below. Stated alternatively, the exemplary motion control linkage system <b>400</b> illustrated as part of the vehicle <b>1000</b> described and illustrated herein below may replace the motion control linkage system <b>300</b> on the vehicle <b>100</b> of <figref idref="DRAWINGS">FIGS. 1-10</figref>, and vice versa, without departing from the scope of the invention.

0075<figref idref="DRAWINGS">FIGS. 11A-11B</figref> illustrates perspective rear views of the mower <b>1000</b> with some structure removed to better illustrate portions of the motion control linkage system <b>400</b>. <figref idref="DRAWINGS">FIG. 11A</figref> provides a more inclusive view illustrating upwardly extending control links <b>412</b> (similar to the links <b>312</b> described herein) connecting drive control levers <b>402</b> of the control area <b>200</b> with the rest of the control system, while <figref idref="DRAWINGS">FIG. 11B</figref> is an enlarged view of a lower portion of <figref idref="DRAWINGS">FIG. 11A</figref>.

0076As shown in <figref idref="DRAWINGS">FIG. 11A</figref>, the motion control linkage system <b>400</b> may (like the system <b>300</b>) include a first or left drive control lever <b>402</b><i>a </i>and a second or right drive control lever <b>402</b><i>b </i>pivotally attached to the chassis <b>102</b>. The control levers <b>402</b> may, like the levers <b>302</b> already described herein, be configured to pivot about a transverse horizontal axis <b>407</b> from a first or neutral position towards both a first or forward stop bar <b>404</b>, and a second or rearward stop bar <b>406</b>.

0077Like the control levers <b>302</b>, the control levers <b>402</b> may be biased to an intermediate, neutral position located generally between the two stop bars <b>404</b> and <b>406</b> as already described herein. That is, each control lever <b>402</b> may be movable between at least the first or neutral position (shown in <figref idref="DRAWINGS">FIG. 11A</figref>), which corresponds to a first or zero forward velocity of its respective drive wheel <b>106</b>/pump <b>110</b>, and a second or engaged position (abutting the forward stop bar <b>404</b>), which corresponds to a second or maximum forward velocity of its respective drive wheel/pump. As a result, each control lever <b>402</b> may independently vary a velocity of its respective drive wheel <b>106</b> incrementally between a first or zero forward velocity and a second or predetermined maximum forward velocity without varying the engine throttle. Accordingly, the control levers <b>402</b> (and stop bars <b>404</b> and <b>406</b>) are substantially identical, and behave in a substantially identical way, to the control levers <b>302</b> (and stop bars <b>304</b> and <b>306</b>) already described herein.

0078As with the system <b>300</b>, each control lever <b>402</b> may also include a secondary lever arm that pivotally receives an upper end of one of the control links <b>412</b>. Each control link <b>412</b> may be segmented and include an adjustment mechanism <b>414</b> to lengthen or shorten the control link during or after installation. As a result of this construction, movement of either control lever <b>402</b> towards the forward stop bar <b>404</b> (or towards the rear stop bar <b>406</b>) results in movement of the respective control link upwardly (or downwardly).

0079<figref idref="DRAWINGS">FIG. 11B</figref> is a partial enlarged rear perspective view of a lower portion of the motion control linkage system <b>400</b>. The platform <b>112</b> and the variable drive units, e.g., pumps <b>110</b>, are also visible in this view. However, various other structures (e.g., engine <b>104</b>, left wheel/motor, platform lift mechanism <b>1220</b>, and portions of the chassis <b>102</b>) are removed to better illustrate the system <b>400</b>. As this view illustrates, the control linkage system <b>400</b> may include independent linkages for each side of the mower <b>1000</b>, e.g., a linkage for each control lever <b>402</b><i>a </i>and <b>402</b><i>b </i>and its respective pump <b>110</b><i>a </i>and <b>110</b><i>b</i>. While the system <b>400</b> is illustrated in the figures as separate mechanisms to independently control a drive wheel <b>106</b> on each side of the mower <b>1000</b>, control systems for alternate applications may utilize a single linkage without departing from the scope of the invention.

0080As further illustrated in <figref idref="DRAWINGS">FIG. 11B</figref>, a lower portion of one side of the control linkage system <b>400</b> may operatively connect one control link <b>412</b> (e.g., link <b>412</b><i>b</i>) to its respective pump <b>110</b> (e.g., pump <b>110</b><i>b</i>). This connection is achieved in the illustrated embodiment with the use of a pivot link or bellcrank <b>416</b> associated with the chassis <b>102</b>, which may be supported such that it is pivotable relative to the chassis, about a main pivot <b>418</b> defining a horizontally transverse main pivot axis <b>420</b>. Unless otherwise stated herein, the other pivots described herein may also pivot about axes that are parallel to the main pivot axis <b>420</b>.

0081As further shown in <figref idref="DRAWINGS">FIG. 11B</figref>, each bellcrank <b>416</b> may include a first arm defining a first end <b>422</b> that is offset from the main pivot <b>418</b>. The first end <b>422</b> of each bellcrank <b>416</b> may be pivotally connected to a proximal end of its respective control link <b>412</b> at a control link pivot <b>424</b> for pivoting about an axis <b>417</b>. Each bellcrank <b>416</b> may also include a second arm defining a second end <b>426</b> offset from the main pivot <b>418</b> and pivotally connected to a first end <b>427</b> of a drive link <b>428</b> at a first drive link pivot <b>430</b> defining a first drive link pivot axis <b>419</b>. A second end <b>429</b> of each drive link <b>428</b> may pivotally connect to a distal end of a pump input member or arm <b>432</b> at a second drive link pivot <b>434</b> defining a second drive link pivot axis <b>421</b> (see also <figref idref="DRAWINGS">FIG. 12</figref>). The input arm <b>432</b> may pivot about an input pivot (defining an input pivot axis <b>433</b>; see <figref idref="DRAWINGS">FIG. 12</figref>) relative to a housing of the pump, thereby repositioning an internal swashplate within the pump to alter the flow of hydraulic fluid delivered to the respective wheel motor <b>107</b> (see also <figref idref="DRAWINGS">FIG. 11A</figref>).

0082<figref idref="DRAWINGS">FIG. 12</figref> illustrates a front perspective view of a portion of the control linkage system <b>400</b>. As shown in this view, the arms <b>432</b><i>a </i>and <b>432</b><i>b </i>may be of different shapes to, for example, accommodate movement of the arms relative to mower structure (not shown).

0083As <figref idref="DRAWINGS">FIG. 12</figref> further illustrates, the platform <b>112</b> may include a tab <b>435</b> that, in the illustrated embodiment, protrudes upwardly between the two pumps <b>110</b>. The tab <b>435</b> may incorporate a proximity sensor that cooperates with a proximity target <b>425</b> on one or both of the pump input arms <b>432</b> to provide an electrical signal corresponding to one or both of the arms being in a pump-neutral position. The platform <b>112</b> may further include one or more stops <b>439</b> to limit the pivotal movement of one or both input arms <b>432</b> during operation. In the illustrated embodiment, a stop <b>439</b> is provided for the right side pump <b>110</b><i>b </i>only. The linkage for the left side pump <b>110</b><i>a </i>may be adjusted to provide an output corresponding to that of the pump <b>110</b><i>b </i>when both control handles <b>402</b> are in the second or full forward position.

0084As shown in <figref idref="DRAWINGS">FIGS. 11B and 13</figref>, each side of the control linkage system <b>400</b> may further utilize a first reference link <b>446</b> (e.g., <b>446</b><i>a</i>) and a second reference link <b>448</b> (e.g., <b>448</b><i>a</i>). These two links may, as described below, locate the bellcrank <b>416</b> in space and support it relative to the chassis <b>102</b>. Stated alternatively, instead of physically attaching the main pivot <b>418</b> directly to a location on the chassis <b>102</b>, the first and second reference links may be used to support and locate the main pivot in space, e.g., to ultimately fix the location of the main pivot <b>418</b> relative to the chassis <b>102</b>. However, that ultimate location may be adjustable as further described below.

0085<figref idref="DRAWINGS">FIG. 13</figref> illustrates a side elevation view of the system of <figref idref="DRAWINGS">FIGS. 11A-11B</figref> and <b>12</b> with the left pump <b>110</b><i>a </i>removed for clarity. The first reference link <b>446</b> may, as shown, be a single link, (e.g., a welded, unitary link having portions <b>446</b><i>a </i>and <b>446</b><i>b</i>; see <figref idref="DRAWINGS">FIG. 11B</figref>), or alternatively be two independent links. As indicated in this view, the first reference link <b>446</b> may include a first end that is pivotally connected to the pivot link (e.g., to the bellcrank <b>416</b>) for pivoting about the main pivot axis <b>420</b> of the main pivot <b>418</b>, and a second end pivotally connected to the platform <b>112</b> such that it is pivotable about a first reference pivot axis <b>451</b> (defined by a first reference pivot <b>450</b>). In the illustrated embodiment, the first reference pivot axis is coincident with the input pivot axis <b>433</b> (see also <figref idref="DRAWINGS">FIG. 12</figref>). Similarly, each second reference link <b>448</b> may include a first end pivotally connected to the pivot link (e.g., to the bellcrank <b>416</b>) for pivoting about the main pivot axis <b>420</b> of the main pivot <b>418</b>, and a second end pivotally connected to the chassis <b>102</b> (e.g., at a location <b>105</b>) such that it is pivotable about a second reference pivot axis <b>423</b> defined by a second reference pivot <b>452</b>. While illustrated as utilizing two links <b>448</b><i>a </i>and <b>448</b><i>b</i>, embodiments utilizing only a single second reference link are also contemplated.

0086As a result of this configuration, the first end of the first reference link <b>446</b> may be capable of movement along a first arc <b>454</b> defined by the first reference pivot axis <b>451</b> of the first reference pivot <b>450</b>, while the first end of the second reference link <b>448</b> may be capable of movement along a second arc <b>456</b> defined by the second reference pivot axis <b>423</b> of the second reference pivot <b>452</b>. The intersection of the first ends of the first and second reference links (e.g., the intersection of the first and second arcs <b>454</b>, <b>456</b>) may define the location of the main pivot axis <b>420</b> of the main pivot <b>418</b>.

0087At least the second reference link <b>448</b> may be configured as an adjustable-length tie rod. Accordingly, a radius of the second arc <b>456</b> may be altered, e.g., the point of intersection of the first arc <b>454</b> with the second arc <b>456</b> may be changed to provide adjustment to the location of the main pivot <b>418</b>. As one can appreciate, however, once the length of the second reference link <b>448</b> is set (e.g., its jam nuts are appropriately tightened), the main pivot <b>418</b> may be generally fixed in space. In other embodiments, the second reference link may be non-adjustable, i.e., fixed in length.

0088With this general overview, the operation of the control linkage system <b>400</b> will now be described with reference primarily to <figref idref="DRAWINGS">FIGS. 13-16</figref>. These figures illustrate a side elevation view of the vehicle <b>1000</b> and system <b>400</b> under various vehicle operating scenarios. In each of these views, various mower structures, e.g., the left wheel and corresponding hydraulic motor (although the input arm <b>432</b><i>a </i>is still shown), engine <b>104</b>, and the left hydraulic pump <b>110</b><i>a</i>, among other components, may be removed to better illustrate system operation.

0089<figref idref="DRAWINGS">FIG. 13</figref> represents the geometry of the system <b>400</b> when the drive control lever <b>402</b> is in the first or neutral position (see solid line representation of the control lever <b>302</b> in <figref idref="DRAWINGS">FIG. 5</figref>) and the platform <b>112</b> is in the first or fully raised position. Conversely, <figref idref="DRAWINGS">FIG. 14</figref> represents the geometry of the system <b>400</b> when the drive control lever <b>402</b> is in the second or engaged position (see broken line representation of the control lever <b>302</b> in <figref idref="DRAWINGS">FIG. 5</figref>) while the platform remains in the fully raised position (while illustrated in <figref idref="DRAWINGS">FIG. 13</figref> (as well as <figref idref="DRAWINGS">FIG. 15</figref>), the mechanism <b>1220</b> is removed from <figref idref="DRAWINGS">FIG. 14</figref> (and from <figref idref="DRAWINGS">FIG. 16</figref>)). As is visible in <figref idref="DRAWINGS">FIGS. 13-14</figref>, movement of either control lever <b>402</b> may vary a position of the respective pump input arm <b>432</b> relative to the pump housing. Thus, as with the system <b>300</b>, incremental movement of the drive control lever <b>402</b> from the first or neutral position to the second or fully engaged position causes the pump input arm <b>432</b> (to which the drive link <b>428</b> is attached) to pivot, relative to the pump housing, from a first or pump neutral position (wherein the pump input arm is approximately vertical, e.g., about 12 o'clock as shown in <figref idref="DRAWINGS">FIG. 13</figref>), to a second or maximum position (wherein the pump input arm is rotated slightly counterclockwise as shown in <figref idref="DRAWINGS">FIG. 14</figref>, e.g., to about eleven o'clock). As described below, this relationship between control levers <b>402</b> and their respective input arms <b>432</b> exists regardless of whether the platform is in (or is moving between) the first position, the second position or any intermediate position.

0090<figref idref="DRAWINGS">FIGS. 15 and 16</figref> are views similar to <figref idref="DRAWINGS">FIGS. 13 and 14</figref>, respectively, but with the platform <b>112</b> shown at its second or fully lowered position (as opposed to the first or fully raised position shown of <figref idref="DRAWINGS">FIGS. 13-14</figref>). <figref idref="DRAWINGS">FIG. 15</figref> illustrates the drive control lever <b>402</b>/system <b>400</b> in the neutral position, while <figref idref="DRAWINGS">FIG. 16</figref> illustrates the system when the control lever is in the full forward position. The platform height adjustment may be accommodated with the lift mechanism <b>1220</b> (see <figref idref="DRAWINGS">FIGS. 13 and 15</figref>) in a manner substantially identical to that already described herein with respect to the lift mechanism <b>220</b> illustrated in <figref idref="DRAWINGS">FIGS. 3A-3B</figref>. Once again, as the platform <b>112</b> and deck <b>114</b> move from the elevation of <figref idref="DRAWINGS">FIGS. 13-14</figref> to the elevation of <figref idref="DRAWINGS">FIGS. 15-16</figref>, movement occurs along the arc <b>255</b> defined by the distance <b>256</b> of each of the bellcranks <b>230</b> and <b>240</b> (see also <figref idref="DRAWINGS">FIG. 3A</figref>). Moreover, as the platform/cutting deck move, each drive link <b>428</b> may pivot about the first drive link pivot <b>430</b> from the position shown in <figref idref="DRAWINGS">FIGS. 13 and 14</figref> to the respective positions shown in <figref idref="DRAWINGS">FIGS. 15 and 16</figref>. Similarly, the first reference link <b>446</b> may pivot about the main pivot <b>418</b> from the position of <figref idref="DRAWINGS">FIGS. 13-14</figref> to that of <figref idref="DRAWINGS">FIGS. 15-16</figref>.

0091With reference to, for example, <figref idref="DRAWINGS">FIG. 15</figref>, the system <b>400</b> may utilize a drive link <b>428</b> having an effective length <b>436</b> (e.g., linear distance measured between pivot axes of the first and second drive link pivots <b>430</b> and <b>434</b>) that is equal to the effective length <b>256</b> of the platform bellcranks <b>230</b> and <b>240</b> (a length measured between the pivot axes of the pivot <b>232</b>/<b>242</b> and the pivot <b>247</b> of each bellcrank). Moreover, a line <b>257</b> extending orthogonally between the axis of the platform chassis pivot <b>232</b>/<b>242</b> and the axis of its associated platform pivot <b>247</b> may be parallel to a line <b>558</b> extending orthogonally between the pivot axes of the first and second drive link pivots <b>430</b> and <b>434</b> at all platform elevations.

0092Furthermore, the first reference link <b>446</b> may have an effective length <b>536</b> (e.g., linear distance measured between the axis <b>433</b>/<b>451</b> of the first reference pivot <b>450</b> and the main pivot axis <b>420</b>) that is equal to the effective length <b>256</b> of the platform bellcranks and the effective length <b>436</b> of the drive link <b>428</b>. Moreover, a line <b>538</b> extending orthogonally between the first reference pivot axis <b>451</b> of the first reference pivot <b>450</b> and the main pivot axis <b>420</b> of the main pivot <b>418</b> may be parallel to both the line <b>257</b> and the line <b>558</b> at all platform locations.

0093As further illustrated in <figref idref="DRAWINGS">FIG. 15</figref>, a linear distance <b>437</b> between the input pivot axis <b>433</b> and the second drive link pivot axis <b>421</b> (see also <figref idref="DRAWINGS">FIG. 11B</figref>) of the second drive link pivot <b>434</b> may be equal to a linear distance <b>438</b> between the main pivot axis <b>420</b> and the first drive link pivot axis <b>419</b> of the first drive link pivot <b>430</b>, while a line <b>560</b> extending orthogonally between the input pivot axis <b>433</b> and the second drive link pivot axis <b>421</b> may be parallel to a line <b>562</b> extending orthogonally between the main pivot axis <b>420</b> and the first drive link pivot axis <b>419</b>.

0094As a result of this geometry, and in a manner similar to that of the system <b>300</b> already described herein, the drive link <b>428</b> may accommodate pivoting of the platform <b>112</b> without imparting any unintended displacement to the input arm <b>432</b> of the pump. Thus, the platform <b>112</b>/cutting deck <b>114</b> may be moved to any available height without altering the position of the pump input arm <b>432</b>. The linkage system may therefore maintain, as the platform <b>112</b> is moved between its first and second positions, both the position of the input member <b>432</b> relative to the drive unit <b>110</b>, and a position of the control link <b>412</b> (as well as the control lever <b>402</b>) relative to the chassis <b>102</b>.

0095While the control system is shown in the neutral position in <figref idref="DRAWINGS">FIG. 15</figref>, the same result may occur regardless of the position of the drive control lever <b>402</b>. For instance, placement of the drive control lever <b>402</b> in the second (e.g., forward) or engaged position (broken lines in <figref idref="DRAWINGS">FIG. 5</figref>) with the platform <b>112</b> at its lowest setting as shown in <figref idref="DRAWINGS">FIG. 16</figref> would result in positioning the pump input arm <b>432</b> in the same location as it is positioned when the platform is at its highest setting (see <figref idref="DRAWINGS">FIG. 14</figref>). In fact, the platform <b>112</b> could even be repositioned during operation (while the control handles remain in a given position) without any effect on pump input/mower speed.

0096The system <b>400</b> may offer several advantages. For instance, like the system <b>300</b>, it may achieve mechanical interconnection of the control handles to the pumps without the use of cables, the latter which may require periodic adjustment/maintenance. Further, adjustment of the pump input arm <b>432</b> of the system <b>400</b> relative to the corresponding drive control lever <b>402</b> may be accomplished with a single adjustment to the length of the second reference link <b>448</b> rather than multiple adjustments required with other systems. Accordingly, both manufacturing and maintenance tasks may be simplified. Moreover, the adjustability of the second reference link <b>448</b> may allow less stringent manufacturing tolerances during vehicle manufacture.

0097Embodiments of the instant application may therefore provide a motion control system and vehicle incorporating the same. Control systems configured in accordance with embodiments of the present invention may include a linkage for accurately adjusting a parameter (e.g., velocity) of the vehicle even as a geometric relationship between an input (e.g., velocity control lever) and an output (e.g., drive train) of the vehicle is modified. Other embodiments may further address velocity limiting mechanisms, illustrative embodiments of which are described herein, that may be used in conjunction with, or independently of, the exemplary motion control system. Still other configurations could incorporate elements of a control system in accordance with embodiments described herein at or near the control area to permit adjustment (e.g., change in elevation) of the location of the drive control levers.

0098Illustrative embodiments of this invention are discussed and reference has been made to possible variations within the scope of this invention. These and other variations, combinations, and modifications in the invention will be apparent to those skilled in the art without departing from the scope of the invention, and it should be understood that this invention is not limited to the illustrative embodiments set forth herein. Accordingly, the invention is to be limited only by the claims provided below and equivalents thereof.